Melt-adhesives for sealing off rocks or building materials

ABSTRACT

Polyamide hot-melt adhesives based on the reaction products of polymeric fatty acids, C 14 -C 18  monocarboxylic acids, C 6 -C 12  dicarboxylic acids and diamines which do not contain any water-extractable, environmentally toxic constituents, which are suitable for sealing cavities in soils, in rock formations, building structures and/or walls, in particular for sealing tunnels, galleries, shafts, channels or caverns, to protect against the penetration of water or the penetration of liquids or gases which contain hazardous substances.

[0001] This invention relates to hot-melt adhesives based onpolyaminoamides and the use thereof for sealing cavities and cracks insoils, in rock formations, building structures and/or walls.

[0002] Walling and cavities in soils, rocks or in mines, in particularin building structures, such as tunnels, galleries, shafts, channels andcaverns, have to be sealed in order to provide protection frompenetration by water or penetration by liquids or gases containingdangerous substances. For this purpose, a liquid sealing materials isintroduced under pressure (injected) into the adjoining rock or theadjoining soils via a sealed drilled hole.

[0003] Known injection liquids are cement suspensions, solutions ordispersions of polyurethane resins or epoxide resins and liquidmulti-component polyurethane resins or epoxide resins. These injectionliquids have the disadvantage of very long curing times which cannot beadjusted exactly. In large building structures, such as tunnels, thisproduces severe technical difficulties, in particular when it leads toso-called “back-flow”, that is when there are cracks, gaps, pores orfissures at the surface of the rock or masonry through which theinjection liquids may escape before they have cured. This means thatsufficient injection pressure cannot be built up so that the cracks,fissures or cavities are not sufficiently filled which results indefective sealing. Hitherto, in these cases, it has proved helpful toseal the fissures found at the surface with a rapid-setting mortar or touse a particularly rapid-curing injection resin at the escape points.Furthermore, it is difficult to introduce these injection resins in sucha way that shrinkage during the curing process does not jeopardise thesealing function. DE-A-19728088 suggests a method for sealing structuralparts by injecting gel-forming waterglass solutions in which thewaterglass solution is mixed with esters or an aqueous curing solutionwhich contains alkali metal aluminates, salts of alkaline earth metalcations, acidic water-soluble salts, glyoxal or organic acids orcompounds thereof, before feeding to the site of injection or whenemerging from the site of injection. This converts the waterglasssolution into a gel. Although these types of gel-forming systems may beformulated so that gel production takes place very rapidly, they havethe critical disadvantage that they do not have a high gap-bridgingeffect, in particular if these gaps are also intended to be sealedagainst water which is under pressure.

[0004] To overcome these technical difficulties in the processesdisclosed hitherto, WO 00/12863 suggests a process for sealing rock orbuilding materials and a device for this in which hot hot-melt adhesiveswith a low viscosity and rapidly produced initial strength are injectedunder high pressure into the rock or building material via the drilledhole, whereupon they penetrate into the fissures and pores in the rockor building material to be sealed. After the hot-melt adhesive cools andsolidifies, the pores and fissures are sealed and permanently closed up.It is suggested that polyamides or gels with polyamide-like propertiesare used for this purpose. No data about the composition of the hot-meltadhesives suitable for this purpose are given in this document. Inparticular, no data at all on ecological compatibility are given.

[0005] Starting from the prior art, the inventor has noted the object ofproviding polyaminoamide hot-melt adhesives which are suitable for thepreviously mentioned objective of sealing cavities in soils, in rockformations, building structures and/or walls.

[0006] The solution according to the present invention is given in theclaims. It consists substantially of the provision of polyaminoamidesbased on the reaction products of polymeric fatty acids, C₁₄-C₁₈monocarboxylic acids, C₆-C₁₂ dicarboxylic acids and diamines which donot contain any water-extractable or environmentally toxic constituents.

[0007] Another important aspect of the polyaminoamide hot-melt adhesivesaccording to the present invention is the provision of a suitableviscosity/temperature profile so that they have a sufficiently lowviscosity at temperatures of about 190-200° C. for them to be injectedinto masonry or rock formations in sufficient volume, using availablepumps, without the use of an unacceptably high build-up of pressure andwithout thermal decomposition of the hot-melt adhesive. Furthermore, thehot-melt adhesive must have a rapidly produced initial strength.

[0008] By heating the polyamide hot-melt adhesives with a rapidlyproduced initial strength, thes are converted into a low viscosity statewhich means that they may penetrate into even the smallest fissures,pores, cracks, etc. in rock and building materials. The hot-meltadhesives are injected into the drilled hole under pressure and fromthere out into the pores and fissures of the rock or building material,wherein the temperature of the hot-melt adhesive decreases with depth ofthe pores so that, as from a specific depth of penetration from thedrilled hole, which depends on the initial temperature, the hot-meltadhesive becomes more and more viscous and finally solidifies. As aresult of the pressure of the hot-melt adhesive following behind, thehot-melt adhesive which has already become more viscous is pushed stilldeeper into the pores or fissures. If the hot-melt adhesives have beenheated to a sufficiently high temperature, they are hot enough for theliquid heated hot-melt adhesive to be able to penetrate deeply into thepores of the rock or building material before they cool and solidify. Tosupport this process, the adjoining rock, masonry or soil may bepre-heated prior to injection.

[0009] On contact with water, the hot-melt adhesives take up a limitedamount of water which increases the volume of the hot-melt adhesive. Thehot-melt adhesive expands further into the pores and fissures whichmeans that the rock or building material is even more tightly sealed. Ifthe sealed rock or building material is subjected to water or moisture,then a structure is built up, due to the increase in volume of thehot-melt adhesive as a result of absorbing water, which may withstandeven a high hydrostatic pressure over the long term.

[0010] When using hot-melt adhesives according to the present invention,the injection process is preferably repeated several times, wherein thehot-melt adhesive which has already penetrated into fissures and poresin the rock or building material to be sealed may at least slightly coolbetween injection processes and fresh, heated hot-melt adhesive maypenetrate into other fissures and pores during the next injectionprocess.

[0011] The advantage of this “stop-go” procedure is that even whenback-flow of the hot-melt adhesive takes place (e.g. due to fissureswhich lead to the surface of the rock or masonry), nevertheless a rapid,reliable build up of pressure is possible. In conventional processes,e.g. when using epoxide resins, in the event of back-flow occurring thecorresponding fissures have hitherto still had to be sealed with “rapidsetting mortar” or very rapid curing epoxide resins have had to be usedat the escape points; these are very difficult to handle under theconditions of application due to their short pot lives. In addition, asa result of the “stop-go” process which is possible using hot-meltadhesives according to the present invention, shrinkage of the hot-meltadhesive during cooling is also compensated for by the hot-melt adhesivewhich is forced to follow on.

[0012] For deep penetration of the heated hot-melt adhesive into therock or building material, it is an advantage if, before injecting theheated hot-melt adhesive into the rock or building material, atemperature gradient is set up in the rock or building material by apre-heating procedure. In order to prevent premature consolidation dueto cooling by the cold rock or building material, this is heated beforeintroducing the hot-melt adhesive.

[0013] By pre-heating the rock or building material to be sealed, it isalso possible to use hot-melt adhesive with a rapidly produced initialstrength which has been heated to a lower temperature for sealingpurposes because it does not solidify immediately at the surface of thecold rock or building material, due to the already elevated temperatureof the rock or building material.

[0014] The heated hot-melt adhesives are preferably introduced into thedrilled hole with a temperature between 50 and 300° C., particularlypreferably between 130 and 250° C. and with a pressure of 1 to 500 bar.The pressure and temperature of the hot-melt adhesive depends on thecharacteristics thereof, on the density, degree of fissuring or porosityof the rock or building material and on the ambient temperature and thedepth of penetration of hot-melt adhesive required and the thermalstability thereof.

[0015] Hot-melt adhesives which may be processed under the previouslymentioned boundary conditions, must therefore satisfy four basicprerequisites:

[0016] they must be thermally stable over the long term in order towithstand repeated heating to the application temperature withoutdecomposing.

[0017] they must have a very low melt viscosity at the applicationtemperatures of between about 130 and 250° C. and at the same time havea high initial strength on cooling and solidifying.

[0018] they should have no constituents which may be extracted in waterand have environmentally toxic properties.

[0019] they must have a sufficiently long open time to be injected intothe cavities in adequate amounts per unit of time.

[0020] According to the present invention, polyaminoamides may be usedfor a high specification application of this type which are preparedfrom the following components:

[0021] 20-99 mol. %, preferably 30-95 mol. %, of dimeric or polymericfatty acids

[0022] 0-50 mol. %, preferably 0-30 mol. %, of C₁₄-C₁₈ monocarboxylicacids

[0023] 0-80 mol. %, preferably 5-70 mol. %, of C₄-C₁₂ dicarboxylic acids

[0024] 20-85 mol. % of aliphatic diamines

[0025] 0-70 mol. % of cycloaliphatic diamines

[0026] 0-60 mol. % of polyoxyalkylene diamines

[0027] 0-50 mol. %, preferably 0-30 mol. %, of monofunctional amines.

[0028] Dimeric or polymeric fatty acids, in the context of the presentinvention, are those fatty acids which are prepared in a known manner bydimerising unsaturated long-chain fatty acids obtained from naturallyoccurring raw materials and are then further purified by distillation.Technical grade dimeric fatty acids contain, depending on the degree ofpurity, up to 5 wt. % of monobasic fatty acids, substantially C₁₈ fattyacids, 60-95 wt. %, sometimes up to 98 wt. %, of C₃₆ dibasic fatty acids(dimeric fatty acids in the stricter sense) and 1-35 wt. % of C₅₄ andhigher polybasic fatty acids (“trimeric fatty acids”). The relativeratios of monomeric, dimeric and trimeric fatty acids in the polymericfatty acid mixture depends on the nature of the starting compounds usedand on the conditions of polymerisation, dimerisation or oligomerisationand the extent of separation by distillation. Dimeric fatty acidspurified by distillation contain at least 70 wt. %, preferably 80 wt. %and frequently 95-99 wt. % of dimeric fatty acids. In a further processstep, these dimeric fatty acids may also be hydrogenated.

[0029] In addition to the dimeric or polymeric fatty acids, the acidcomponent of the polyamide may also contain C₄-C₁₄ dicarboxylic acids.Examples of these types of dicarboxylic acids are maleic acid, succinicacid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylicacid, glutaric acid, suberic acid, pimelic acid or also aromaticdicarboxylic acids, such as terephthalic acid or mixtures of thepreviously mentioned dicarboxylic acids.

[0030] The diamine component consists substantially of one or morealiphatic diamines, preferably with an even number of carbon atoms,wherein the amino groups are at the ends of the carbon chain. Thealiphatic diamines may contain 2 to 20 carbon atoms, wherein thealiphatic chain may be linear or slightly branched. Particularlypreferred aliphatic diamines are C₄-C₁₂ diamines with an even number ofcarbon atoms.

[0031] The amino component may also contain cyclic diamines orheterocyclic diamines, such as 1,4-cyclohexane diamine,4,4′-diaminodicyclohexylmethane, piperazine,cyclohexane-bis-(methylamine), isophorone diamine, dimethylpiperazine,dipiperidylpropane and dimeric diamines (amines prepared from dimericfatty acids).

[0032] In addition, if the polyaminoamide in intended to have highflexibility, polyoxyalkylene diamines, such as polyoxyethylene diamine,polyoxypropylene diamine or bis-(diaminopropyl)-polytetrahydrofuran, mayalso be used. The polyoxyalkylene diamines also known as “Jeffamines”(tradename of the Huntsman Co.) are particularly preferred. Themolecular weight of the Jeffamines used is between 200 and 4000,preferably between 400 and 2000.

[0033] Hot-melt adhesives to be used according to the present inventionmay also contain polyepoxides, polyols and polyesters as additionalstructural components.

[0034] By selecting the short-chain diamines and the short-chaindicarboxylic acids and also the purity of the dimeric fatty acids, boththe viscosity and the viscosity/temperature profile and also thesoftening point of the hot-melt adhesive may be adjusted in such a waythat the hot-melt adhesive is suitable for the use according to thepresent invention. The hot-melt adhesive should have a melt viscosity of50-10,000, preferably 100-4000 mPa.s, at 180° C. measured in accordancewith ASTM D 3236, so that the hot-melt adhesive may be efficientlypumped in the temperature range between 180 and 250° C. usingconventional pumps and so that it may be injected into the area ofapplication without any difficulty. A polyaminoamide hot-melt adhesivewhich is extremely suitable for the process according to the presentinvention has, for example, a viscosity of 450 mPa.s at 190° C., stillhas a viscosity of 250 mPa.s at 200° C. and still has a viscosity of 125mPa.s at 230° C. The softening point of a hot-melt adhesive of this typeis about 185° C., measured using the “ring and ball” method ASTM E 28.

[0035] Polyaminoamide hot-melt adhesives have to be protected fromthermal and oxidative degradation with the aid of stabilisers, inparticular when they are subjected to thermal stress which is as high asthat in the case of applications according to the present invention. Thestabilisers usually used for this purpose, e.g. based on arylphosphates, are not suitable for introduction into water-bearing layersof rock or soil regions. Although they are very effective with regard tothe stabilising effect thereof on the hot-melt adhesive, tests havedemonstrated that these stabilisers may be extracted by water and thatwater contaminated in this way has a high toxic effect on daphnia andalgae. Hot-melt adhesives stabilised in this way would contaminate theadjoining groundwaters and therefore cannot be used for this purpose forecological reasons. According to the present invention, thosestabilisers are preferably used which have already been firmlyincorporated into the polyamide molecule during the polycondensationprocess, that is the manufacturing process for the polyamide. Thesestabilisers are incorporated so firmly in the polymer structure thatthey cannot be extracted by water. Therefore the use of hot-meltadhesives of this type does not lead to any ecological damage, even inwater-bearing rock or soil formations. The toxicity value of thestabiliser used (determined as the EC50 value in mg/l) should be as highas possible and the water-solubility (in mg/l) of the stabiliser shouldbe as low as possible. The water-solubility of the stabiliser usedshould preferably be well below about 0.5 mg/l and the EC50 value fordaphnia magna or algae should be greater than about 50 mg/l.Particularly suitable stabilisers are, for example, long-chainarylalkylamines or pentaerythrityltetrakis(3-(3,5-di-tert.-butyl-4-hydroxyphenyl) propionate (Irganox1010, Ciba Specialty Chemicals).

[0036] The present invention is explained in more detail using thenon-limiting Examples given below.

EXAMPLES

[0037] The polyamide hot-melt adhesive “Macromelt TPX 20-345” (HenkelKGaA) was selected for the following Examples. This hot-melt adhesivehas a viscosity of 450 mPa.s at 190° C., still has a viscosity of 250mPa.s at 200° C. and still has a viscosity of 125 mPa.s at 230° C. Itssoftening point is 185° C., measured by the “ring and ball” method, ASTME 28. The adhesive contained a dialkylarylamine as stabiliser.

[0038] Tests on “Bolesta radial flow” showed that this hot-melt adhesivemay be injected. The test arrangement used was in accordance with thedata given in “Arbeitsgruppe Felsinjektion, SchluBbericht, May 1984”,pages 61-63.

Example 1

[0039] Test arrangement: Polyamide hot-melt adhesive “Macromelt TPX20-345” (Henkel KGaA, Düsseldorf) was heated to 220° C. and injected at150 bar (machine pressure) into a 1 inch water pipe which was filledwith soil material. To ensure a heat reservoir, a small cavity was madeat the inlet point. The transfer piece was preheated using a hot airblower. After completing injection of the polyamide, a pressure checkwas performed with compressed air in the opposite direction to that ofthe initial injection.

[0040] The pipe was filled with dry chippings (about ⅜ mm, smallproportion of dust) and the test arrangement was connected directly tothe feed-point for hot-melt adhesive. After completing injection of thepolyamide, it was shown that the hot-melt adhesive had completely filledthe entire length of the piece of test pipe (2 m); a pressure testshowed that the filling was pressure-tight up to the maximum achievablepressure of 10 bar of compressed air. Then a pressure test was performedusing oil pressure; the filling was pressure-tight up to 10 bar.

Example 2

[0041] Test arrangement same as in Example 1. The pipe was filled with amixture of sand, gravel and chippings with a high proportion of finematerial, saturated with water and compacted by slurrying.

[0042] It was shown that the depth of penetration of hot-melt adhesivewas up to about 1.2 m. A pressure test showed that the filling waspressure-tight up to the maximum achievable pressure of 10 barcompressed air. Then a pressure test was performed using oil pressure,wherein it was shown that the filling was pressure-tight up to themaximum achievable oil pressure of 60 bar.

[0043] The two trials 1 and 2 demonstrated very rapid sealing againsthigh water pressure (up to 60 bar) with long-term effectiveness.

Example 3

[0044] Test arrangement (similar to that in the “Bolesta” method):“Macromelt TPX 20-345” (Henkel KGaA, Dusseldorf) was heated to 220° C.and injected at 150 bar (machine pressure) in the molten state betweentwo exposed aggregate concrete slabs. The distance between the slabs wasabout 2 mm. The space between the slabs was sealed with a rubber sealantin such a way that the air found therein could be displaced. The slabswere fixed firmly in place with wires in order to prevent any lifting.

[0045] Within a few seconds after staring to inject the polyamide, thegap between the slabs was filled completely. Due to the pressure, acrack was produced in the upper slab, through which polyamide emerged.After a few minutes of curing time, polyamide was injected once more andthis melted the polyamide already present so that more injectionmaterial emerged from the gap.

[0046] This Example demonstrates that complete filling of gaps andfissures in rocks or masonry is easy and simple to perform.

Example 4

[0047] To check for environmental compatibility, test sheets with thedimensions 16 cm×13 cm×2 cm were prepared from the polyamide hot-meltadhesive and subjected to a migration test using the trough method.Here, three test sheets were each placed in contact with 2.3 l ofdeionised water in sequence for 1 day, 2 days and finally 4 days at roomtemperature. After each contact period, the test water was withdrawncompletely for analysis and replaced by fresh deionised water. Inaddition to the overall composition of the test water, the release oforganic substances was determined on the basis of organically bondedcarbon (TOC) and the release of substances which are capable of couplingwas determined in accordance with DEV H 16 (phenol index).

[0048] Furthermore, the test water from the first and third migrationperiods were subjected to toxicity tests according to DIN 38412 part 33(algal growth test), DIN 38412 part 11 (daphnia test) and the luminousbacteria test (DIN 38412 L 34/341). The test water was not noticeablyaffected with regard to color, turbidity or the tendency to form foam.The release of organic compounds (TOC) varied between 1.3 and 2.2 mg/land is assessed as being very low; it decreased substantially during thetrial period. The migration of substances capable of coupling (phenolindex) fell to 0.008 mg/l over the course of the test. It should benoted here that the limit of detection is about 0.005 mg/l; water withthis type of low phenol index is of drinking water quality. The daphniatoxicity decreased greatly from the first trial stage to the third trialstage; the EC50 value changed from 400 g of eluate/l to 950 g ofeluate/l. The inhibitory effect of the test water on algal growth alsoshowed very little toxicity. The daphnia toxicity and the inhibitoryeffect of the test water on algal growth are classified as “zero” atdilutions likely to be encountered in practice. This value is based on asuggestion by Th. Grunder, H-P. Lühr, W. Rummel and R. Stock(“Entwicklung und Erprobung eines System zur Bewertung und Einstufingder ökologischen Verträglichkeit von Produkten hinsichtlich ihrerGrundwasser- und Bodengefährdung”, IWS at TU Berlin, AZ:05624). Thedetermination of luminous bacteria toxicity gave a value of GL=3 fortest water from the first stage; this means that the eluate has onlynegligible luminous bacteria toxicity.

[0049] These toxicity data demonstrate that hot-melt adhesives to beused according to the present invention do not produce any unacceptableeffects in groundwater.

Example 5 (Comparison)

[0050] A hot-melt adhesive with the same polymer composition as in theprevious Examples, which contained isodecyldiphenyl phosphate as astabiliser in accordance with the prior art, was subjected to theenvironmental compatibility tests described in Example 4. The followingvalues were found:

[0051] Phenol index 0.3 mg/l, this value remained constant at the samehigh value even after long elution times

[0052] TOC: between 3.3 and 5.6 mg/l

[0053] Daphnia toxicity, G_(D)=10, no tendency to decrease over the testperiod,

[0054] Algal toxicity, G_(D)=50 to 100, no tendency to decrease over thetest period.

[0055] These values show that a conventionally stabilised hot-meltadhesive releases toxic substances into the eluate water for anunacceptably long time and therefore is not suitable for use ingroundwater-bearing formations.

1. Polyamides based on the reaction products of polymeric fatty acids,C₁₄-C₁₈ monocarboxylic acids, C₆-C₁₂ dicarboxylic acids and diamines,characterised in that they do not contain any water-soluble orwater-extractable environmentally toxic constituents.
 2. Polyamidesaccording to claim 1 wherein 20 to 99 mol. %, preferably 30 to 95 mol.%, of dimeric or polymeric fatty acids 0 to 50 mol. %, preferably 0 to30 mol. %, of C₁₄-C₁₈ monocarboxylic acids 0 to 80 mol. %, preferably 5to 70 mol. %, of C₄-C₁₂ dicarboxylic acids 20 to 85 mol. % of aliphaticdiamines 0 to 70 mol. % of cycloaliphatic diamines 0 to 60 mol. % ofpolyoxyalkylene diamines 0 to 50 mol. %, preferably 0 to 30 mol. %, ofmonofunctional amines are used as structural components.
 3. Polyamidesaccording to claim 1 or 2 wherein the water-soluble or water-extractableconstituents have a daphnia toxicity EC50 of >300 g eluate/l or thatwhen the test water is diluted at a rate of 1:10, these have no toxiceffects in accordance with DIN 38412 part 11 on daphnia.
 4. Polyamidesaccording to claims 1 to 3 having a melt viscosity of 50 to 10,000,preferably 100 to 4000 mPa.s, at 190° C. measured according to ASTM D3236.
 5. Use of polyamides according to claims 1 to 4 to seal cavitiesin soils, rock formations, building constructions and/or walls.
 6. Useaccording to claim 5 for sealing tunnels, galleries, shafts, channels orcaverns.